Intra-tooth stable isotope analysis of human dental tissues: laser ablation of enamel and serial sections of dentine collagen in permanent first molars and canines

Sandberg P, Passey B, Lee-Thorp J, Sponheimer M, Ditchfield P, Van Gerven D

Time series stable isotope analysis in dental tissues has become a useful tool for investigating diet histories in a variety of modern and fossil animals, but has only recently been applied to humans in archaeological contexts. The permanent human dentition preserves chronological dietary information for approximately the first two decades of life, as enamel and dentine do not turn over once fully mineralized. A time interval of particular interest to anthropologists is that which captures the weaning process, as the timing and nature of this life history event have crucial ramifications for a number of important demographic variables; however, conventional methodologies have lacked the resolution to describe these events in much detail. Methodological advances in laser ablation isotope analysis have made it possible to measure carbon and oxygen isotope ratios in-situ with tremendous spatial precision providing an opportunity to greatly refine chronological isotopic profiles in human enamel. New methods for incremental sampling of human dentine collagen have been developed that greatly improve the resolution of carbon and nitrogen isotope chronologies within this tissue as well. In this study, we combined these techniques for the first time to compare isotope sequences in enamel and dentine collagen of permanent first molars and canines from five individuals from Kulubnarti, an Early Christian site in Sudanese Nubia (500-800 A.D.). The results indicate that both methods reveal considerable isotopic variability within teeth and among individuals, produce comparable patterning, and hold future promise for reconstructing human dietary and life histories for archaeological and paleontological applications.